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The Food and Drug Administration regulates medical devices used in the application of phototherapy.

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Key Takeaways

How much the joints respond to light therapy varies, and your doctor may suggest other treatments.

The scheduling of phototherapy proves daunting to many prospective patients.

Psoriatic arthritis often takes a multitherapy approach to treat. One component of that may be light therapy, or phototherapy, which offers an effective and low-risk option for treating mild to moderate psoriasis.

The Food and Drug Administration regulates medical devices used in the application of phototherapy, and limited evidence suggests that joints affected by the disease will respond to treatment targeted to the skin. “You do get a systemic modulation of the immune system. It’s interesting that when you treat the skin, the joints respond,” says Jami Miller, MD, assistant professor of medicine and dermatology, and supervisor of the phototherapy clinic, at Vanderbilt University Medical Center in Nashville, Tennessee.

Just how much the joints respond varies, and it’s important to understand that your medical team may suggest other treatment for your psoriatic arthritis. “This type of arthritis needs to be controlled by drugs — it can be very destructive if it’s not treated aggressively,” says Yusuf Yazici, MD, a rheumatologist at NYU Langone's Center for Musculoskeletal Care in New York City.

Types of UV Light Treatment for Psoriasis

Your doctor may suggest one or more of the following UV phototherapy or combination therapy approaches:

Ultraviolet A (UVA) One of the most common options is short bursts of UVA, typically starting at 30 seconds in length and building in duration as a patient adapts to the exposure. A conventional treatment schedule calls for three sessions per week for 4 to 50 sessions, until the psoriasis has cleared. “We typically go for 20 sessions at first,” says Dr. Miller. “If we don’t see anything at all after 20 sessions, we rethink the treatment.”

Ultraviolet B (UVB)The Mayo Clinic notes that coal tar treatment makes skin more receptive to light, so some doctors combine UVB and coal tar treatments for a more effective therapy. The combination once required a three-week hospital stay, but a modification can be performed in a doctor's office, according to Mayo.

PUVA (psoralen and UVA) For advanced cases of psoriasis, a physician might suggest augmenting UVA treatment with an oral medication called psoralen. Taken shortly before light treatment, psoralen seems to boost the therapeutic effect of light on the immune system. “PUVA is spectacularly effective,” says Miller. Because PUVA can be so powerful, the treatment is rarely used in children.

Cautions About UV Light Therapy

There are many factors to consider if you're thinking of undergoing light therapy:

Darker complexions may not respond as well. While phototherapy for psoriasis can be used regardless of your complexion type, light-skinned people typically respond to treatment more quickly than those with darker skin, Miller says.

Scheduling can be difficult. The scheduling of phototherapy proves daunting to many prospective patients, Miller says. The biggest deterrent is the hassle of traveling to a treatment site several times a week for a regimen that can extend for months. Another complication is that patients who augment UVA treatment with psoralen must wear protective sunglasses when outdoors for 24 hours afterward to protect their eyes against natutally occurring UVA in sunlight.

Light therapy is not as widely available as it used to be. Psoriasis phototherapy is generally less available than it was 10 or 20 years ago, because there are more treatments for psoriasis now and insurance coverage for phototherapy has become less available, Miller says. And it can be expensive: The cost of a single phototherapy session can reach $150, particularly if the treatment is provided in combination with psoralen or another systemic drug.

PUVA carries some cancer risk.According to the National Psoriasis Foundation (NPF), narrow-band, or low-energy, UVB is effective in treating psoriasis for at least two-thirds of patients. Narrow band UVB is thought to have less skin cancer risk than PUVA, according to the NPF, which recommends that people regularly get their skin examined by their healthcare provider. "The break seems to be at 250 sessions in a lifetime, so we do try to limit it," says Miller.

Insurance Issues With Light Therapy

The National Psoriasis Foundation (NPF) has reported that patients have had difficulty getting insurance coverage for light therapy. Lack of insurance coverage, or cost, was one of the top three reasons patients discontinued phototherapy.

That’s not surprising given the typical pattern of phototherapy insurance coverage, says Lawrence Green, MD, associate professor of dermatology at the George Washington University School of Medicine in Washington, DC. “Phototherapy in general costs between $60-90 a treatment and you need to go at least twice a week for a few months minimum to achieve clearance of psoriasis,” says Dr. Green. “This quickly gets quite expensive. Even if you have insurance, there are often copays of up to $50 per visit in many plans. And these copays seem to be going up every year!”

Because of the costs and the time commitment involved, undertaking light therapy is a decision that requires a lot of thought. To help you determine whether this therapy makes sense for you, talk over the possible advantages with your medical team.

“It is important to keep multiple therapies in the therapeutic armamentarium as different people respond variably to different treatments,” says Miller.